1. Field of the Invention:
The present invention relates to a head moving device, and more particularly to a head moving device for linearly and intermittently moving a head a predetermined unit amount.
2. Description of the Prior Art:
Various devices have been developed for recording signals along concentric tracks of a disc-shaped rotary recording medium, for reproducing the recorded signals, or for doing both. The medium may be in the form of a magnetic or optical disc such as a floppy disc or video disc. In such devices it is necessary to move a recording or reproducing head intermittently along the radial direction of the record bearing medium, in predetermined discrete amounts, that is, the pitch of the recording tracks on the record bearing medium.
It is essential to position the head correctly in order to record a signal at a predetermined position on the record bearing medium. Such positioning makes the medium interchangeable with other apparatus during recording and allows proper reproduction without track deviation.
A head moving device that linearly moves the head in response to rotation of a motor is normally constructed such that an indexing member rotated by the motor within one revolution over the head's whole range of movement is provided with an arresting element (for example, a click stop element) to arrest the rotated member at each track position of the head. Thus, movement of the head a predetermined amount is controlled by arresting the rotated member in a rotational phase corresponding to each track position of the head.
However, to record signals at, for example, fifty different positions on the recording medium, the indexing member must be correctly arrested in fifty different rotational phases. Therefore, for example, when a click stop element is used as the arresting element, fifty click grooves must be correctly indexed and formed on the indexing rotation member. However, it is very difficult in practice to index and form this many click grooves correctly. First, it is impossible to move the head by a predetermined unitary amount with high precision due to inferior indexing accuracy. Further, the indexing rotation member is very expensive and its dimension or diameter must be unavoidably large to obtain high accuracy. This is quite inconvenient.
Also, this kind of device has to be provided with a mechanism for adjusting the head position on the record bearing medium.
The most conventional head adjusting mechanism positions the head by adjusting the position of the head relative to a head carriage which supports the head. However, in order to realize this effect, the construction for producing the position adjustment becomes large and complicated, the contact of the head with the medium is at times inferior, and the part to be adjusted is very close to the head, so that the danger of damaging the head during adjustment is high, while complicated and inconvenient handling is necessary.